Respiratory function detection

Abstract

A system and method for monitoring respiratory function that includes an acoustic sensing device sensing an acoustic waveform ocurring during one of an inspiration phase associated with at least one breath of a patient and an expiration phase associated with at least one breath of a patient, and a processor configured to determine changes in high frequency acoustic amplitude associated with the sensed acoustic waveform and, in response to the determined changes in high frequency acoustic amplitude, determine an indication of respiratory function.

1 . A method for monitoring respiratory function, comprising:
 sensing an acoustic waveform ocurring during one of an inspiration phase associated with at least one breath of a patient and an expiration phase associated with at least one breath of a patient;   determining changes in high frequency acoustic amplitude associated with the sensed acoustic waveform; and   determining an indication of respiratory function in response to the determined changes in high frequency acoustic amplitude.   
     
     
         2 . The method of  claim 1 , further comprising:
 determining changes in low frequency acoustic amplitude associated with the sensed acoustic waveform; and   determining the indication of respiratory function in response to the determined changes in low frequency acoustic amplitude, wherein determining an indication of respiratory function further comprises:
 determining a first indication of respiratory function in response to determined changes in high frequency acoustic amplitude; and 
 determining a second indication of repiratory function different from the first indication of respiratory function in response to determined changes in low frequency acoustic amplitude. 
   
     
     
         3 . The method of  claim 2 , further comprising:
 receiving a first thoracic impedance waveform for at least one breath of a patient;   determining a first breath slope value in response to on the first thoracic impedance waveform; and   comparing the first breath slope value to a first threshold slope value of the patient, wherein determining an indication of respiratory function further comprises determining the indication of respiratory function in response to the comparing.   
     
     
         4 . The method of  claim 3 , further comprising determining whether the first thoracic impedance waveform was collected in response to a first activation event, wherein the first threshold slope value is a first baseline slope value and wherein the first baseline slope value is associated with the first activation event. 
     
     
         5 . The method of  claim 4 , further comprising:
 comparing the first thoracic impedance waveform to the first baseline impedance waveform, the first baseline impedance waveform collected in response to a baseline activation event, the baseline activation event corresponding to the first activation event;   in response to the comparing the first thoracic impedance waveform to the first baseline impedance waveform, detecting a change in patient status;   in response to a detected change in patient status, associating the first thoracic impedance waveform with the new patient status; and   storing the new patient status and the first impedance waveform.   
     
     
         6 . The method of  claim 4 , further comprising:
 receiving a second thoracic impedance waveform;   determining whether the second thoracic impedance waveform was collected in response to a second activation event different from the first activation event;   determining a second breath slope value in response to the second thoracic impedance waveform;   comparing the second breath slope to a second baseline slope value associated with the second activation event;   comparing a difference between the first breath slope value and the first baseline slope value and a difference between the second breath slope value and the second baseline slope value; and   in response to the comparison of the differences, determining whether a change in relative respiratory function has occurred.   
     
     
         7 . The method of  claim 1 , further comprising:
 determining an area under the curve of the at least one breath, and   comparing the area under the curve of the at least one breath to a threshold area under the curve value; wherein determining an indication of respiratory function of the patient further comprises determining the indication of respiratory function of the patient in response to the comparison of the area under the curve of the at least one breath.   
     
     
         8 . The method of  claim 7 , wherein the area under the curve for the breath is the area under the curve during inspiration. 
     
     
         9 . The method of  claim 7 , wherein the area under the curve for the breath is the area under the curve for expiration. 
     
     
         10 . The method of  claim 3 , wherein the first breath slope value is a long term average of inspiration slope value, the method further comprising determining a ratio between the long term average of inspiration slope value and a long term average of expiration slope value. 
     
     
         11 . A system for monitoring respiratory function, the system comprising:
 an acoustic sensing device sensing an acoustic waveform ocurring during one of an inspiration phase associated with at least one breath of a patient and an expiration phase associated with at least one breath of a patient; and   a processor configured to determine changes in high frequency acoustic amplitude associated with the sensed acoustic waveform, and determine an indication of respiratory function in response to the determined changes in high frequency acoustic amplitude.   
     
     
         12 . The system of  claim 11 , wherein the processor is further configured to determine changes in low frequency acoustic amplitude associated with the sensed acoustic waveform, and determine the indication of respiratory function in response to the determined
 changes in low frequency acoustic amplitude, wherein determining an indication of respiratory function further comprises:
 determining a first indication of respiratory function in response to determined changes in high frequency acoustic amplitude; and 
 determining a second indication of repiratory function different from the first indication of respiratory function in response to determined changes in low frequency acoustic amplitude. 
   
     
     
         13 . The system of  claim 12 , the system comprising:
 an impedance sensor, the impedance sensor configured to collect a first thoracic impedance waveform for at least one breath of a patient; and   a memory configured to store a first threshold slope value, wherein the processor is further configured to determine a first breath slope value in response to the impedance waveform, and compare the first breath slope value to a first threshold slope value, wherein determining an indication of respiratory function further comprises determining the indication of respiratory function in response to the comparing.   
     
     
         14 . The system of  claim 13 , wherein the processor is further configured to determine whether the first thoracic impedance waveform was collected in response to a first activation event, wherein the first threshold slope value is a first baseline slope value and wherein the first baseline slope value is associated with the first activation event. 
     
     
         15 . The system of  claim 14 , wherein the processor is further configured to:
 compare the first thoracic impedance waveform to the first baseline impedance waveform, the first baseline impedance waveform collected in response to an original activation event, the original activation event corresponding to the first activation event;   detect a change in patient status in response to the comparing the first thoracic impedance waveform to the first baseline impedance waveform;   in response to a change in patient status, associate the first thoracic impedance waveform with the new patient status; and   store the new patient status and the first impedance waveform in the memory.   
     
     
         16 . The system of  claim 14 , wherein
 the impedance sensor is further configured to collect a second thoracic impedance waveform; and   the processor further configured to:
 determine whether the second thoracic impedance waveform was collected in response to a second activation event different from the first activation event; 
 determine a second breath slope value in response to on the second thoracic impedance waveform; 
 compare the second breath slope to a second baseline slope value associated 
   with the second activation event;
 compare a difference between the first breath slope value and the first baseline 
   slope value and a difference between the second breath slope value and the second baseline slope value; and
 in response to the comparison of the differences, determine whether a change 
   in relative respiratory function has occurred.   
     
     
         17 . The system of  claim 13 , wherein the processor is further configured to:
 determine an area under the curve of the at least one breath;   compare the area under the curve of the at least one breath to a threshold area under the curve value; and   determine the indication of respiratory function in response to the comparison of the area under the curve of the at least one breath.   
     
     
         18 . The system of  claim 17 , wherein the processor is configured to determine the area under the curve during inspiration. 
     
     
         19 . The system of  claim 17 , wherein the processor is configured to determine the area under the curve during expiration. 
     
     
         20 . The system of  claim 13 , wherein the processor is further configured to determine a long term average of inspiration slope value, determine a long term average of expiration slope value, and determine a ratio between the long term average of inspiration slope value and the long term average of expiration slope value. 
     
     
         21 . A computer-readable medium comprising instructions for causing a programmable processor to:
 sense an acoustic waveform ocurring during one of an inspiration phase associated with at least one breath of a patient and an expiration phase associated with at least one breath of a patient;   determine changes in high frequency acoustic amplitude associated with the sensed acoustic waveform; and   determine an indication of respiratory function in response to the determined changes in high frequency acoustic amplitude.